PCI-Express UltraStudio and Teranex

It has been two and a half years since the introduction of Thunderbolt and the adoption on the Windows PC camp has been almost non-existent, aside from a couple of motherboard manufacturers. The major workstation manufacturers (HP, Dell and Lenovo) have yet to announce new models with Thunderbolt ports, and they don't seem to be in a hurry to do so. Since Thunderbolt has to be implemented on the motherboard and cannot be added through a PCI card, I was wondering why Blackmagic Design does not offer PCIe versions of their Thunderbolt products so they can be used in Windows Workstations. Is there any technical reason why they can't offer PCIe versions of at least their flagship products; UltraStudio 4k and Teranex?.

Yes, I know there are plenty of alternatives for windows PCs, and they only require one or two PCIe slots; they are affordable but not elegant. By the way what's the deal with Multibridge Pro2 and Multibridge Eclipse?, I noticed they are no longer advertised in the BMD web site but you can still order them from the resellers. Are these two products compatible with the latest editions of Media Composer, Adobe CC, and Resolve?.